The present invention relates to a cartridge magazine for a gun and especially to a conversion cartridge magazine for use in converting a gun to a smaller caliber.
The present invention is a magazine adapter principally for use with automatic and semi-automatic firearms, such as pistols, which magazines can conventionally have a magazine body with a floor plate and a spring in the magazine body having a cartridge follower to move the cartridges forward. As each cartridge is chambered, the next cartridge moves forward in the magazine under spring pressure. In recent years, it has become common practice to convert pistols and rifles to use a different caliber bullet than the firearm had been originally manufactured for. This has been particularly the case in the conversion of larger caliber firearms to .22 caliber automatic pistols and rifles. Firearms of this character are favored for target practice and training and have a reduced cost of ammunition over the larger caliber firearms.
The present invention is adapted for use in converting a Colt Army .45 caliber (Model M1911A1) for use with .22 caliber rimfire cartridge but may be used with any conversion desired. In the typical automatic or semiautomatic firearms, each cartridge is moved forward by the magazine spring pushing the follower and the cartridges. The follower has a forwardly moving slide and the weapon loads each cartridge by moving the top cartridge into the chamber. In addition to converting the magazine, the conversion of a firearm requires that the barrel be sized for the new cartridge and the receiver be such as to be able to fire a rimfire cartridge in place of a center fire cartridge and have sufficient recoil to drive the receiver back to eject one cartridge shell while chambering the next cartridge shell.
The present invention is directed towards a converted firearm cartridge magazine for converting to a smaller caliber, which magazine is made of a machined metal, such as machined aluminum alloy, and has rapidly interconnecting parts and which also is adapted to support a coiled spring for use as a magazine spring. The machined alloy allows the magazine to be made the same size as the larger caliber magazine on the outside while the inside is machined for the smaller size cartridges without having to otherwise take up the slack. It has been suggested in the past to form a magazine of a molded plastic body but such magazine body tends to be more prone to breakage and damage in normal use.
Prior art magazines for use in conversion of the calibers of firearms or for extending the magazines in automatic weapons can be seen in U.S. Pat. No. 2,396,816 to Boudreau which has a magazine conversion unit and special adapter for use in connection with magazines to permit the magazine to hold and the gun to fire cartridges of lesser firing power but of the same caliber than the gun is normally adapted for. The Baldus et al. U.S. Pat. No. 4,862,619, is a Magazine Adapter made of a one-piece cast or molded polymer magazine for use with an extended magazine for a firearm and includes a magazine adapter that attaches to the bottom of the handle of a pistol for holding a smaller magazine in a specially formed area. The Baldus et al. patent also includes a floor plate for the spring which has a slide type floor plate detentably secured against removal by the sidetracks formed by the rolled flanking edges of the magazine and which plate serves as a retainer against the thrust of a follower spring.
The Farrar et al. U.S. Pat. No. 4,514,922, is a Gun Magazine Structure for holding a series of rounds of ammunition and has a floor plate at the lower end of the magazine detachable therefrom by a sliding movement relative to the body. The floor plate of the magazine is connected to the magazine body loosely and is held in place by locking means for blocking lateral separation of the floor plate from the magazine body and held from sliding by the pressure from the spring. The Foote U.S. Pat. No. 4,139,958, is for a Magazine Adapter Assembly for Firearms for conversion of an automatic or semiautomatic shotgun or rifle to a smaller caliber. The Day U.S. Pat. Nos. 3,772,812 and 3,724,326, each show Sub-Caliber Conversion Units including a sub-caliber magazine insert attachably secured in the magazine of a larger caliber pistol so that the pistol can use sub-caliber cartridges. The Elbe et at. U.S. Pat. No. 4,079,535 is a Magazine for a rimfire adapter to feed cartridges into a rifle. The Jurek U.S. Pat. No. 4,069,608, is a .22 caliber rimfire adapter system for an M16 rifle and the Elbe et al. U.S. Pat. No. 4,058,922, is a Rifle Adapter Assembly for converting a rifle to fire ammunition of different shape or type of caliber than the rifle was originally designed for.